19336-93-7

Upstream product

• 6307-13-7 2-(2-hydroxyphenyl) isoindoline-1,3-dione 
• 85-44-9 phthalic anhydride 
• 95-55-6 2-amino-phenol 

Downstream Products

• 85-44-9 phthalic anhydride 
• 95-55-6 2-amino-phenol 
• 827-27-0 sodium 1,2-benzenedicarboxylate 
• 30798-41-5 sodium 2-aminophenolate 

Relevant academic research and scientific papers

Intramolecular carboxylic group-assisted cleavage of N-(2-hydroxyphenyl)- phthalamic acid (7) and N-(2-methoxyphenyl)-phthalamic acid (8): Absence of intramolecular general acid catalysis due to 2-OH in 7

The values of pseudo first-order rate constants (kobs) for the cleavage of AM 2-hydroxyphenyl)phthalamic acid (7), obtained at 4.9 × 10-2 M HCl, 35°C, and within CH3CN content range 2-80% (v/v) in mixed aqueous solvent are smaller than kobs for the cleavage of N-(2-methoxyphenyllphthalamic acid (8), obtained under almost similar experimental conditions, by nearly 1.5- to 2-fold. These observations show the absence of expected intramolecular general acid catalysis due to 2-OH group in 7. The values of kobs for the cleavage of 7 and 8 decrease by more than 20-fold with the increase in the content of CH3CN from 2 to 80-82% (v/v) in mixed aqueous solvent. The kinetic data reveal that in acidic aqueous cleavage of 7, N-cyclization (leading to the formation of imide) and O-cyclization (leading to the formation of phthalic anhydride) vary from ～10 to 15% and ～90 to 85%, respectively, with the increase in CH 3CN content from 2 to 80% (v/v). Similar increase in CH3CN content causes increase in N-cyclization from ～0 to 5% and decrease in O-cyclization from ～100 to 95% in the acidic aqueous cleavage of 8. Some speculative, yet conceivable, reasons for nearly 10 and 0% N-cyclization in the cleavage of respective 7 and 8 at low content of CH3CN have been described.

Efficient rate enhancement due to intramolecular general base (IGB) assistance in the hydrolysis of N-(o-hydroxyphenyl)phthalimide

The rates of the hydrolyses of N-(o-hydroxyphenyl)phthalimide (1) and N-(o-methoxyphenyl)phthalimide (2), studied at different pH, show that the hydrolysis of 1 involves intramolecular general base (IGB) assistance where the o-O- group of ionized 1 acts as IGB and H2O as the reactant. The rate enhancement due to the IGB-assisted reaction of H 2O with ionized 1 is >8 × 104-fold. Pseudo-first-order rate constant for the reaction of water with 2 is ～2 × 103-fold smaller than the first-order rate constant (0.10 s-1) for pH-independent hydrolysis of 1 within the pH range of 9.60-10.10. Second-order rate constants (kOH) for hydroxide ion-assisted hydrolysis of ionized 1 and 2 are 3.0 and 29.1 M-1 s-1, respectively. The solvent deuterium kinetic isotope effect (dKIE) on the rate of alkaline hydrolysis of 1 and 2 reveals that the respective values of kOH/kOD are 0.84 and 0.78, where kOD represents the second-order rate constant for DO--assisted cleavage of these imides (1 and 2). The value of kwH2O/k dD2O is 2.04, with kwH2O and k dD2O representing pseudo-first-order rate constants for the reactions of ionized 1 with H2O and D2O, respectively.

Determination of pKa of ammonium and phenolic groups: Evidence of intramolecular hydrogen bonding in aqueous solution

The ionization constants of 2-hydroxyanilinium, 2-methoxyanilinium, 4-nitroanilinium ions, N-(2′-hydroxyphenyl)-phthalamic acid and N-(2′-methoxyphenyl) phthalamic acid, determined spectrophotometrically, have been rationalized in terms of internal hydrogen bonding and steric hindrance between o-substituent and reaction site.